Automatic latching device



- July 4, 1933- E. T. SPRAKE AUTOMATIC LATCHING DEVICE Filed Dec. 17, 1951 Patented July 4, 1933 uNrrE s'ra'res PATENT oFFicE EDMUND T. SPRAKRDF PLYMOUTH, FENNSYLVANIA, ASSIGNOR F ONE-FOTTRTH TO J'QHN IDAUGHERTY, OF PLYMOUTH, PENNSYLVANIA, ONE-FOURTH TO LAZAR'US j LOWE AND ONE-FOURTH T0 0. E. MATTER, BOTH 0F KINGSTON, PENNSYLVANIA H AUTOMATIC LATCHING DEVICE Application filed. December 1?, 1931. Serial No. 581,617.

The present invention relates to latching devices for doors and the like.

The invention has found application to doors of water tube boilers as for instance inspection doors whichmay be opened while the boiler is under pressure. For safety, recent regulations require such doors to be equipped with latches of positive locking type, without reliance on springs or friction contacts.

The principal object of the present invention is to provide such an automatic positive latch, which is fool proof, simple in design, and of low first cost in production and installation and of low cost in maintenance.

The invention will be described in connection with its application to boiler doors. It is to be understood, however, that it may have many other applications in which it is desired to latch automatically one plane surface to another.

The invention will be described and its advantages pointed out in connection with the attached drawing which shows a form of the invention chosen for illustration, in which the latch comprises a one piece casting, a steel supporting stud, a castellated nut, a cot ter pin and a steel stop pin.

7 1 In the drawing,

Figure 1 is a front elevation of my device.

Figure 2 is an end View of Figure 1.

Figures 3, 1 and are views of the latch casting. I

Figure 6 is a front elevation of a portion of my device in door opening position U In the embodiment of my invention chosen for illustration in the drawing, my device is shown as including a latch casting provided with a cylindrical body portion 1 surrounded by a heavy eccentric flange 2. Flange 2 is cut away as indicated at 3 in Figure 3 to form a plane tangent to the cylindrical body 1. The latch casting is provided with two projecting cam surfaces 4: and 5. Cam surface l is normally the opening cam and is a segment of a spheroid. Cam surface 5 is the.

latch cam and is a plane surface. The casting is also provided with a projecting counterweight 6 and a lug 7. The cylindrical body 0 of the casting is provided with a bore 8 for the reception of a supporting stud 9. Stud 9 carries a castellated nut 10 which secures the latch casting pivotally upon the stud v9.

The latch casting is pivotally mounted upon the door frame 12 of a boiler door 13 which swings on hinge 14. Door 13 is provided with a door latch 15 cooperating with a latch lug 16 to secure the door 13 in closed position. Door 13 carries a door handle 17 which is rotatable vertically into the position shown by the dotted lines in F igure 2. To prevent the complete rotation of the latch casting there is provided a stop pin 19 in the door frame 2 against which the lug 7 bears when the latch is in the door open position. When the door is in closed position a' portion of flange 2 overlies the door and secures it 'in closed position as is shown in Fi ures 1 and 2.

In operation assuming the doorto be closed and the latch in position shown in Figures 1 and 2, with the flange 2 overhanging the door and locking it shut, against the frame, to open the door the handle 17 is rotated upward as indicated in the dotted lines of F igure 2. The handle engages the surface of earn 4 and rotates the latch casting 18 about the stud 9 in clockwise direction until the handle comes in contact with the end of the stud. When the handle reaches this point the casting has been rotated until the cut away portion of the flange 2 lies parallel to and above the top ofth'edoor. The handle then acts as a lever with the end of the stud 9 as a fulcrum to open the door 13 which passes out from under the flange. The projecting counterweight 6 in this position has been rotated to a point where it tends to continue the rotation of the latch casting until the lug 7 comes in contact with the stop pin 19, arresting the latch in the position shown in Figure 6.

WVith the latch in the position shown in Figure 6, to latch the door, the door is swung shut. In swinging the top of the door engages the surface of cam 5, rotating the latch counter clockwise. The top of the door moves under the cut away portion of the flange, continued pressure on the cam 5 rotates the latch until the door is closed against the frame, while the counter weight 6 continues the counter clockwise rotation to the position shown in Figures 1 and 2 with the flange overhanging the door and looking it shut.

Should the latch accidentally have been rotated to the closed position shown in Figures 1 and 2, while the door is open, the latching action on closing is as follows.

The top of the door engages the surface of cam 4. while the door is some distance from its shut position. As the door continues to close the pressure on cam 4 rotates the latch casting in clockwise rotation until the latch casting assumes the position of Figure 6. On continued closing the top of the door engages the surface of cam 5 and the latch casting is rotated counter clockwise, the door closing under the cut away portion of the flange, and continued rotation due to the counter weight bringing the latch to the closed position and locking the door as previously described.

It will be obvious that the apparatus illustrated and described may be modified considerably without departing from the spirit of this invention. For instance, the latch cams, cylinder, flange and counter weight have been described as preferably cast in one piece. They may obviously be made in separate pieces and assembled. Any desirable means of pivoting the latch on the frame may be employed instead of the steel stud and castellated nut and cotter pin.

It is desirable to employ the door handle in the fashion described for opening the door but the latch casting may be rotated by means of the counter weight until the cut away portion of the flange is parallel to and above the door and then the door may be pulled open by any handle which may not necessarily be arranged to coact with the latch cam 4 in opening. I

I do not intend to be limited in the practice of my invention save as the scope of the prior art and of the attached claims may require.

I claim:

1. In a door structure including a door frame and a door'hingedly mounted on said frame, a latch pivotally mounted on said frame adjacent said door, a counterweight on said latch, a cam face on said latch adapted to be engaged'by' said door in closing to rotate said latch in one direction, and a second cam face on said latch adapted to be engaged by said door upon closing to rotate said latch in the opposite direction, and to close said latch upon said door by the action of said counter weight.

2. In a door structure including a door frame and a door hingedly mounted upon said frame, a'latch pivotally mounted adjacent said door, a counter weight on said latch, a cam face on one side of said latch from said counter weight and adapted to be engaged by said door in closing to rotate said latch in one direction, means for limiting the rotation of said latch in that direction, said counter weight being slightly overbalanced in said limitingposition, and a second cam face on said latch on the opposite side of said counter weight from said first mentioned cam face and adapted to be engaged by said door in closing to rotate said latch in the opposite direction and to cause said latch to close against said door under the action of said counter weight.

3. In a door structure including awall having an orifice therein and a door hingedly mounted adjacent said orifice and adapted to close it, a latch pivotally mounted adjacent said door, a counterweight on said latch, a handle pivotally mounted on said door, a cam face on said latch on one side of said counter weight and adapted to be engaged by said handle to rotate said latch in one direction, and a second ca1n face on said latch adapted to be engaged by said door in closing to rotate said latch in the opposite direction and to cause said latch to close upon said door under the action of said counter weight.

4. In a door structure including a door frame and a door hingedly mounted on said frame, a latch pivotally mounted adjacent said door, a pivot on said frame forming the mounting for said latch, a counterweight on said latch, a cam face in the shape of an inclined plane adapted to be engaged by said door when closing to rotate said latch in one direction, a handle mounted on said door and swinging in a plane including said pivot when the door is closed to engage said pivot as a fulcrum to open the door, and a second cam face on said latch in the shape of a curved section adapted to be engaged by said handle to rotate said latch in the opposite direction to which the latch is moved by said first mentioned cam to release the door from said latch.

EDMUND T. SPRAKE. 

